The invention relates generally to devices and methods for controlling heat buildup in an optical package. More specifically, the invention relates to a device and a method for removing excess optical power from a fiber-optic package.
There is an increasing demand for fiber-optic components that can withstand high optical power. This trend is being set due to increased channel count and data rates in optically amplified transmission systems as well as the advent of Raman amplification systems. Power levels that are now being sent through fiber-optic components can be anywhere from 200 to 500 mW. In Raman systems, power in the 1400+ nm wavelength range are promising to be 500 to 1000 mW or even more. Fiber-optic components exposed to such high power levels risk the possibility of sustaining high-power optical damage.
The damage from high continuous-wave optical sources in fiber is due primarily to photo-thermal mechanisms. When materials within a component absorb a fraction of the radiation, the energy most often gets efficiently converted into heat. At very high powers, even small to moderate absorption can result in a significant temperature rise. The critical factor for the component designer becomes how to manage the localized heat buildup due to photo-thermal temperature rises in the component package. The heat buildup can be caused by any material in the package that absorbs light. The heat buildup can also be caused by insertion losses intentionally designed into the component or by unintentional intrinsic material losses or scattering to other parts of the package.
Some fiber-optic components, such as variable optical attenuators, are designed to cause a controlled amount of insertion loss. Some fiber-optic components, such as optical amplifiers, are characterized by some insertion loss that causes their output signal with respect to their input signal to be attenuated. The critical issue for these devices when used in high power environments is what happens to the optical power that has been attenuated. The power has to be discarded or diverted from the component in a safe manner. Otherwise, if the optical energy is dumped somewhere in the component package, it will result in a temperature rise in the package, which can cause significant damage to temperature-sensitive elements within the package or even safety hazards, such as the package melting or catching on fire.
From the foregoing, there is desired a mechanism for removing excess optical power from a fiber-optic package so as to avoid heat buildup that can damage temperature-sensitive elements and/or create safety hazards.